Field of the Invention
The present invention relates to a surface machining method for a single crystal SiC substrate, a manufacturing method thereof, and a grinding plate for surface machining a single crystal SiC substrate.
This application is a national stage under §371 of PCT/JP2014/053379 filed Feb. 13, 2014, which claims priority from Japanese Patent Application No. 2013-026081, filed Feb. 13, 2013, the above-noted applications incorporated herein by reference in their entirety.
Description of Related Art
Since silicon carbide (SiC) as a semiconductor material has a wider band gap than silicon (Si) currently used widely as a substrate for devices, studies are underway to produce power devices, high-frequency devices, high-temperature-operating devices, and the like using a single crystal SiC substrate.
A single crystal SiC substrate is formed by, for example, cutting a single crystal SiC ingot manufactured by using a sublimation method and then machining both surfaces to be minor finished (for example, refer to PTL 1).
Since the cut substrate includes warped portions, undulating portions, or machining strain, the surfaces are polished to be minor finished through chemical mechanical polishing (CMP) after the above-described defects are mitigated through, for example, grinding using diamond abrasive grains. However, since the machining speed of CMP is low, it is highly desirable that the depth of the machining strain layer be decreased as much as possible before CMP (for example, refer to NPL 1).
For the minor-finish machining a non-oxide ceramic such as SiC, a mechano-chemical polishing technique is used. For example, NPL 2 discloses a method for dry polishing carried out on a polishing disc obtained by shaping chromium oxide abrasive grains having an average grain diameter of 0.5 μm with a resin such as acrylonitrile or phenol and results of the machining single crystal SiC.